Tests the contents of a cell for the #NA! error condition and returns TRUE if it finds this error. This function is useful to check the results of formulas that contain the MATCH, LOOKUP, VLOOKUP, or HLOOKUP functions.
Format: ISNA (value)
Argument:
ΓÇó value: Any text, number, cell reference, or function.
Example:
ISNA (TRUE) returns FALSE.
Shows that TRUE is a Boolean expression, not the N/A! error.